Sender: <marv@lancaironline.net> (Marvin Kaye)
To: lml
Date: Wed, 28 Aug 2002 12:41:30 -0400
Message-ID: <redirect-1713463@logan.com>
From: Jim Thomas <mypa12@yahoo.com>
Subject: Icom A-22, Antennas, CTAF Congestion
MIME-Version: 1.0
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I plan to install a handheld nav/comm in my Legacy based on my experience
with the Icom A-22 I have installed in my Piper PA-12.  In my Cub I
originally intended to use the A-22 as my second comm radio.  My initial
thoughts were that it would be too low powered to be very useful, but it
did have the capability to receive nav frequencies and a DVOR and CDI
display.  For several reasons, the Icom has now become my primary comm
radio. 

In my Cub I connected the A-22 to aircraft power so it is not using up
it's own battery power, but if there is a failure in the aircraft power
the A-22 automatically switches to it's own battery pack.  The audio
output is wired to my intercom system so it functions just like a panel
mounted radio.  I initially connected it to an external comm antenna which
worked well for the comm frequencies, but did not work at all for
receiving VOR signals.  My inquiry into this problem led me to learn that
comm signals are vertically polarized and nav signals are horizontally
polarized making it difficult for a comm antenna to pick up the nav
signal.  I solved this problem by installing a nav antenna and now I just
switch antennas when I want to use my A-22 to track a VOR.  I can track
VOR's as far away as 50-75 miles and all works great.   

Here is my question to those of you who know a lot more about radios than
I do.  I have found that I can listen and transmit on the VOR antenna
nearly as well as I can when the A-22 is hooked to the external comm
antenna.  Will transmitting on the nav antenna hurt my A-22 in any way? 
If no damage occur, then I may just leave it hooked to the nav antenna all
the time.  This leads me to want to know if the factory installed nav
antenna in the wing tip of my Legacy can be used as both my nav and comm
antenna for a low power handheld radio without causing any damage?

Now I would like to share why my A-22 has become the primary radio in my
Cub.  First, I have to let you know that my other radio is an Icom A-200
which is only a comm radio with no nav capability.  It has flip-flop
frequency, memory channels, and auto squelch features.  All in all it is a
good radio.   However, I have found that the A-22 has more sensitivity
allowing it to pick up weaker signals farther away.  It has a digital key
pad which makes inputting frequencies a snap.  It has weather channels, it
has the VOR and DVOR capability.  With the A-22 hooked to an external
antenna and aircraft power I have found that I can broadcast at altitude
an easy 25 miles and even more when atmospheric conditions are just right.

Now here is the clincher.  I live on an airport which shares 123.05 with
several other airports in central California.  This frequency is very
busy, especially on weekends and when one particular airport is conducting
skydiving activities.  The jump plane using a full power panel mounted
radio broadcasting "jumpers away" at 12,000 feet literally owns the entire
central California sky on 123.05.  For this reason, I feel using my low
powered A-22 with it's limited broadcast range as my primary radio
actually creates less frequency congestion for the other airports in the
area.  Although I am not knowledgeable in these things, I intuitively
think that our newer radios with more broadcast power and higher
sensitivity are actually causing a congestion problem with the limited
number of CTAFs available.  Are lower powered comm radios something we
should be using more?

I look forward to hearing others experiences and opinions regarding the
use of handheld radios in their aircraft.

Jim Thomas
L2K @ maybe 50%


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